WASHINGTON -- Severely wounded and still recovering, former Rep. Gabrielle Giffords begged federal lawmakers at an emotional hearing Wednesday to act quickly to curb firearms because "Americans are counting on you."

Not everyone agreed, underscoring the national political divide over gun control.

Giffords' 80-word plea was the day's most riveting moment, delivered in a hushed, halting voice two years after the Arizona Democrat suffered head wounds in a Tucson shooting spree that killed six people -- and six weeks after 20 first-graders and six adults were slain by a gunman at Sandy Hook Elementary School in Newtown, Conn.

But at the same session, a leader of the National Rifle Association rejected Democratic proposals to ban assault weapons and high-capacity ammunition magazines and said requiring background checks for all gun purchases would be ineffective because the Obama administration isn't doing enough to enforce the law as it is.

Even if stronger background checks did identify a criminal, "as long as you let him go, you're not keeping him from getting a gun and you're not preventing him from getting to the next crime scene," said Wayne LaPierre, the NRA's executive vice president. He said poor enforcement is "a national disgrace."

Giffords, who left Congress last year, focused during her brief appearance Wednesday on the carnage from armed assailants.

"Too many children are dying," she said at a Senate Judiciary Committee hearing. "Too many children. We must do something. It will be hard, but the time is now."

Guiding her in and remaining to testify was Mark Kelly, the retired astronaut who is Giffords' husband. Giffords and Kelly, both of whom own guns, have formed a political action committee called Americans for Responsible Solutions that backs lawmakers who support gun restrictions.

"We're simply two reasonable Americans who realize we have a problem with gun violence and we need Congress to act," Kelly said.

Wednesday's session played out in a hearing room packed to capacity. While both sides appealed to their followers beforehand to arrive early and fill the room, most in the public audience of around 150 appeared to be gun-control sympathizers, including relatives of people killed in the April 2007 shooting spree at Virginia Tech.

"There should be gun control," said Neeta Datt of Burtonsville, Md., who, with Christa Burton of Silver Spring, Md., was first in line for public seats. Both are members of Organizing for Action, the Obama political organization that is now pushing his legislative agenda.

The hearing kicked off a year in which President Barack Obama and members of Congress are promising to make gun restrictions a top priority. Obama already has proposed requiring background checks for all gun sales and reviving both an assault weapons ban and a 10-round limit on the size of ammunition magazines, and several Democrats have introduced bills addressing those and other limitations.

After the hearing, Giffords met privately with Obama at the White House.

At the Capitol, senators' remarks during the hearing illustrated the gulf between the two parties on this issue.

"Unfortunately, in Washington, emotion ... often leads to bad policies," said Cruz, a freshman elected with strong tea party backing.

Republicans blamed the nation's gun troubles on a list of maladies, including a lack of civility, violent video games and insufficient attention to people with mental health problems.

Sen. Charles Grassley of Iowa, the top Republican on the Judiciary Committee, said that while he welcomed the renewed focus on guns, "the deaths in Newtown should not be used to put forward any gun control proposal that's been floating around for years."

Democrats countered that a need to improve gun restrictions was obvious. Sen. Charles Schumer of New York said omitting gun limits from the debate "is like not including cigarettes when discussing lung cancer."

Republicans and the NRA are not the only hurdles that Democrats face in trying to push gun legislation through Congress this year. It also is unclear what several Democratic senators facing re-election in GOP-leaning states in 2014 will do, including Sens. Max Baucus of Montana, Mark Begich of Alaska and Mark Pryor of Arkansas.

Sen. Patrick Leahy, D-Vt., the committee's chairman, said he hoped his panel would write gun control legislation next month, though he did not specify what it might contain. In his opening remarks, Leahy voiced support for requiring broader background checks that would help keep criminals and the mentally ill from obtaining firearms, and he also has introduced legislation that would make it a federal crime for someone to buy a gun for a person who would not be legally allowed to have one.

Reflecting the emotion that the gun issue taps into nationwide, Wednesday's three-and-a-half-hour hearing featured numerous clashes between senators and some of the witnesses who testified.

"You are a large man," Gayle Trotter, a senior fellow with the conservative Independent Women's Forum, told Sen. Sheldon Whitehouse, D-R.I., as he questioned her about gun curbs he favors. "You are not a young mother who has a young child" she might have to defend, she said.

At other points, Democrats on the panel contested LaPierre's argument that criminals simply would ignore expanded requirements for background checks. Such checks currently area required for gun purchases from licensed dealers, but not for some firearms bought in conjunction with gun shows or online.

"That's the point. The criminals will not go to purchase the guns because there'll be a background check," said Sen. Dick Durbin of Illinois. "It will stop them from original purchase. You missed that point completely. It is basic."

Under questioning from Leahy, LaPierre said that, in a reversal, his organization no longer supports universal background checks for gun purchasers, as it did years ago.

"Back in '99, you said, 'No loopholes, nowhere,'" Leahy SAID, referring to testimony delivered more than a decade ago. "Now you do not support background checks for all."

Giffords, a surprise witness at the hearing, was helped to her chair as the hearing began by Kelly, Leahy and other committee members. She'd been working on her remarks for a week but decided to deliver them Tuesday evening, said Pia Carusone, her former chief of staff who now is executive director for Americans for Responsible Solutions.

Kelly described the January 2011 attack on his wife and others and her battle to regain basic skills.

"Gabby's gift for speech is a distant memory," he told the senators. "She struggles to walk, and she is partially blind. Her right arm is completely paralyzed. And a year ago, she left a job she loved -- serving the people of Arizona."